Just replaced the brakes on my 2003 GMC Envoy, new pads, turned the rotars and they squeak very loud. Any suggestions?

Did you use the exact OEM replacement pads that came on the vehicle? Frequently, squeaks are caused by brake pads that are compounded differently. If the vehicle came with organic pads, stay with them; otherwise, if you switch to semi-metallic pads, for instance, they may squeal and wear the pads and rotors differently. It's also important to apply compounds, like Squeak Relief, to any shims or caliper pins.

Remember to completely change the brake fluid every 2 to 3 years, with an ABS-approved fluid. It helps the calipers to operate properly and prevents corrosion in the calipers and ABS system.

Attention to detail makes a big difference with brakes. This link should help:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-8.html#post1618425